In recent years, digital broadcasting using a broadcasting satellite and digital terrestrial broadcasting have been carried out. On the other hand, distribution of digitized multimedia information, such as music and drama, has been also performed as the Internet has become widespread. As transmission methods of transmitting multimedia information have diversified this way, a receiving apparatus having a function of being able to enable users to selectively view and listen to any of pieces of multimedia information which are transmitted by way of a plurality of transmission systems by using only the single receiving apparatus has appeared. Furthermore, it can be expected that, as a provision method of providing information, a service for broadcasting and distributing some pieces of multimedia information having the same description simultaneously by way of different transmission systems becomes ready.
By the way, in a case in which some pieces of multimedia information having the same description are simultaneously provided by way of different transmission systems, as mentioned above, it can be expected that high-quality multimedia information having a smaller amount of errors is reconstructed if stream data which are received by way of a network system can be used in order to complement transmission errors of a stream which is received by way of a broadcast system.
As a conventional technology, there has been provided a multimedia information receiving apparatus that improves the quality of a video by combining main information which is transmitted by way of a broadcast system and supplement information which is transmitted by way of an IP (Internet Protocol) communication system (for example, refer to patent reference 1). The main information which is handled by this apparatus is I picture data and P picture data having higher priorities which construct video data which comply with the MPEG (Moving Picture Expert Group) 2 standards, while the supplement information is B picture data having a lower priority. These main information and supplement information are generated beforehand by a transmit side in such a way that they are separated from multimedia information, and are transmitted by way of different systems. For example, for a user who desires high quality, the receiving apparatus then combines the main information and the supplement information to reproduce a high quality video. Therefore, the transmit side needs to have equipment which generates different data for one program. However, because according to the conventional technology broadcast data having the same description are not transmitted by way of a different transmission system, it is difficult for the receiving apparatus to make users enjoy a program having an adequate image quality by using only supplement information transmitted by way of, for example, an IP system. Furthermore, patent reference 1 does not refer to any solutions of transmission errors at all.    [Patent reference 1] JP,2003-37571,A
The present invention is made in order to solve the above-mentioned problems, and it is therefore an object of the present invention to provide a multimedia information receiving apparatus that reconstructs multimedia information with the amount of transmission errors being reduced and that enables reproduction of a high-quality image or sound in an environment where two pieces of multimedia information about an identical program are simultaneously transmitted in parallel by way of two different systems, respectively.